[CMake] FindHDF5.cmake improvement proposal

[Biddiscombe, John A.]

> There will be a new FindHDF5.cmake?
> How will my CMakeLists.txt change?

I planned on spending a bit of time on resolving a few last CMake+HDF5 issues before the 1.8.5 branch of hdf is closed (I believe April 15). I had planned on looking at FindHDF5.cmake as clearly a new one will be required.

Will since you're the maintainer of the findhdf5 - have you been using our cmakeified hdf5 and tried a first cut of a new find module (I ask in the hope that you've already done one).

JB